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See detailChemical characterisation and in vitro assessment of the nutritive value of co-products yield from the corn wet-milling process
Malumba Kamba, Paul ULg; Boudry, Christelle ULg; Roiseux, Olivier et al

in Food Chemistry (2015), 166

The chemical characteristics of co-products recovered during a laboratory-scale wet milling procedure as well as that of whole corn flour were characterised and their digestibility and fermentability ... [more ▼]

The chemical characteristics of co-products recovered during a laboratory-scale wet milling procedure as well as that of whole corn flour were characterised and their digestibility and fermentability value determined using a 2 steps in vitro digestibility and fermentation model of the pig digestive tract. Five co-products differing in their chemical composition were collected and analysed. These co-products differed in their in vitro dry matter Digestibility and in their kinetic of fermentation. High coefficients of digestibility were observed for starchy samples, while low coefficients of digestibility were observed for samples rich in lignocellulosic components. Fermentation patterns of samples analysed were different as well as the profile of volatile fatty acids produced during the fermentation. The production of straight-chain fatty acids produced was significantly correlated with the proportion of starch in the sample, while branched-chain fatty acids were correlated to proteins concentration of samples. [less ▲]

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See detailPhysicochemical characterization and in vitro assessment of the nutritive value of starch yield from corn dried at different temperatures
Malumba, P.; Odjo, S.; Boudry, Christelle ULg et al

in Stärke = Starch (2014), 66

To assess modifications induced in starch granules during high temperature drying of corn grain and their effect on the nutritive value of corn-starch, physicochemical and structural characteristics of ... [more ▼]

To assess modifications induced in starch granules during high temperature drying of corn grain and their effect on the nutritive value of corn-starch, physicochemical and structural characteristics of starch granules from corn grains dried at different temperatures have been determined. Additionally, their in vitro digestibility and fermentation patterns were investigated, using a two steps in vitro model of the pig digestive tract. High drying temperatures induced a partial gelatinization of starch granules and produced a very favorable substrate for porcine pancreatic amylase and led to an altered physical structure which affected the rate and extent of starch granules digestion by gastric and pancreatic enzymes. Starch micrographs showed that granules extracted from corn dried at 130°C were less angular, bigger, and had smoother surface than granules extracted from corn dried at lower temperature. High-temperature drying increased the digestibility of wet-milled starch granules, while the residues of starch from corn dried at lower temperature produced higher volume of gas during their in vitro fermentation, despite their more pronounced crystalline characteristic. The residues from pepsin–pancreatic digestion of overall samples analyzed showed highly degraded and pitted granules or fragmented external shells, starch from corn dried at 130°C being the most degraded. Aforementioned changes of nutritional attributes of starch granules are discussed according to the restructuration occurring within both their amorphous and crystalline phase, as well as to the changes of the granules size and purity. [less ▲]

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See detailSuitability of the Weibull 4-parameters model to predict the induction phase of α-amylase production during red sorghum malting when a steep in dilute NaOH is used prior to a resteep in a Bacillus subtilis-S499 based treatment
Bwanganga Tawaba, Jean-Claude ULg; Benjamin Pondo Kouadio; Malumba Kamba, Paul ULg et al

in Journal of the Institute of Brewing (2013)

In previous studies, Bacillus subtilis has been used to control mould growth during red sorghum malting. The use of this biocontrol in steeping liquor has been optimized with some success and the combined ... [more ▼]

In previous studies, Bacillus subtilis has been used to control mould growth during red sorghum malting. The use of this biocontrol in steeping liquor has been optimized with some success and the combined use of a 0.2% NaOH steep, followed by a resteep in a Bacillus subtilis-based biocontrol, has been proposed. The sharpness and variability of the β-amylase peak and the higher levels of β-glucanase obtained in the presence of B. subtilis cells were highlighted. In this work, the suitability of the Weibull 4 Parameters Model to predict sorghum malt α-amylase activity during the enzyme induction stage of red sorghum germination has been compared with those of a 2nd Order Polynomial Model and a General Linear Model. Results obtained showed that the Weibull 4 Parameters Model could be used to predict α-amylase activity, with significant goodness of fit when compared to the 2nd Order Polynomial Model and to the General Linear Model. The effects of steeping treatment (combined use of 0.2% NaOH and Bacillus subtilis S499 starters) and the germination temperature are presented. When the Bacillus subtilis culture used as a starter was diluted, the treatment efficacy to develop α-amylase activity was lost. This study also showed that the germination temperature affected the α-amylase activity rate increase during the induction phase. [less ▲]

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See detailEffect of the use of dilute alkaline prior to Bacillus subtilis-based biocontrol steeping and germination conditions on red sorghum malt β-glucanase activities and residual β-glucans
Bwanganga Tawaba, Jean-Claude ULg; Destain, Jacqueline ULg; Malumba Kamba, Paul ULg et al

in Journal of Cereal Science (2013)

Malting is the ideal stage to deal with β-glucans. Their hydrolysis is very important as the diffusion of both hormones and hydrolytic enzymes in the endosperm of germinated grain depend on it. A high ... [more ▼]

Malting is the ideal stage to deal with β-glucans. Their hydrolysis is very important as the diffusion of both hormones and hydrolytic enzymes in the endosperm of germinated grain depend on it. A high malt β-glucanase activity is not a guarantee of an extensive hydrolysis of β-glucans. When Bacillus subtilis is used to control mould growth, red sorghum malt β-glucanase activity (measured using carboxymethylcellulose as the substrate) was improved without significantly affecting the hydrolysis of malt β-glucans. Thus, in order to reduce the residual β-glucans content, soaking in 0.2% NaOH was combined with a biocontrol. Soaking in 0.2% NaOH is recognized as capable of improving grain hydration by opening-up the endosperm cell walls. The combined use of 0.2% NaOH with Bacillus subtilis-based biocontrol treatments during red sorghum malting, leads to malt with increased β-glucanase activity and a significant reduction of residual β-glucans when compared with the 16 h biocontrol steeping without prior steeping in 0.2% NaOH. β-glucanase activity increases with increased germination temperature and time while, conversely, the residual β-glucans content of the malts decreases. Indeed, while the level of β-glucanase was not vastly different between the malts obtained after steeping in distilled water and those obtained after 8 h steeping in 0.2% NaOH followed by 8 h resteeping in distilled water (NaOH+H2O treatment), their residual β-glucans levels differ significantly. Bacillus subtilis-based treatment leads to malt with improved β-(1-3)- and β-(1-4)-glucanase activities without significantly improved malt β-(1-3),(1-4)-glucanase activity. While malts obtained after 84 h germination weren’t significantly different in terms of malt β-(1-3),(1-4)-glucanase activities for all steeping treatments, the use of 0.2% NaOH steeping prior to resteeping led to malts with improved β-glucans content. Combining the steeping in dilute alkaline and biocontrol enables taking advantage of the dilute alkaline effect on residual β-glucans content, due probably to the opening-up the cell walls and the improvement of water uptake, and that of the biocontrol (improvement of β-glucanase synthesis). [less ▲]

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See detailInfluence of drying and hydrothermal treatments on the denaturation of corn proteins
Odjo, Djosse Psijus Sylvanus ULg; Malumba Kamba, Paul ULg; Bera, François ULg

Poster (2013, February 08)

Corn (Zea mays L.) is the most abundant cereal grain produced in the world. It also provides a significant amount of protein in human and animal diets. During drying corn grains undergo several ... [more ▼]

Corn (Zea mays L.) is the most abundant cereal grain produced in the world. It also provides a significant amount of protein in human and animal diets. During drying corn grains undergo several alterations including protein denaturation. A series of studies have been conducted in order to understand mechanisms behind denaturation of corn proteins during drying and heat moisture treatments. Using a laboratory fluidized-bed dryer, a flint corn variety have been dried between 54° and 130°C and subjected to different analyses from a qualitative point of view with a sequential extraction of corn protein fractions and from a quantitative point of view with the modeling of salt-soluble proteins using Promatest assay. Albumin, globulin and zein solubilities dropped significantly when the drying temperature increased. The electrophoretic patterns of zein and glutelin-G1 were not significantly modified, although the solubility of zein was affected by the drying temperature. The analysis of the different protein group solubilities suggested that denaturation mechanisms other than the creation of new disulfide bonds occurred during the drying of corn at high temperature. The study of the effect of heat treatments on the extractability of salt-soluble proteins shows that temperature; moisture content and time of processing greatly influence their kinetic denaturation. Modeling of salt-soluble proteins reveals that the evolution of extractible salt-soluble proteins content of corn kernels during drying at high temperature is more correctly described with a second order kinetic reaction. Investigations continue in order to understand protein denaturation and influence in functional properties and end-use of corn protein-based products. [less ▲]

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See detailModelling the β-amylase activity during red sorghum malting when Bacillus subtilis is used to control mould growth
Bwanganga Tawaba, Jean-Claude ULg; Bera, François ULg; Thonart, Philippe ULg

in Journal of Cereal Science (2013), 57

Steeping in dilute alkaline (0.2% NaOH) followed by resteeping in biocontrol (starters of Bacillus subtilis S499) has been used during red sorghum malting. The effect of steeping and germination ... [more ▼]

Steeping in dilute alkaline (0.2% NaOH) followed by resteeping in biocontrol (starters of Bacillus subtilis S499) has been used during red sorghum malting. The effect of steeping and germination conditions has been described using 2 functions: a Weibull 4-parameter model combined with a General Linear Model with Logarithm Link with significant goodness. Steeping conditions (combined use of NaOH and Bacillus subtilis S499) affects the synthesis capacity of grain: when Bacillus subtilis culture used in the steeping step is diluted, lnα increases, suggesting a loss of treatment efficacy. The germination temperature affects the β-amylase synthesis rate during the induction phase: the germination temperature increase is accompanied by a decrease of the β-amylase synthesis rate. During the repression phase of β-amylase synthesis, the effect of malting conditions was found to taper. [less ▲]

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See detailThe swelling behaviour of wheat starch granules during isothermal and non-isothermal treatments
Malumba Kamba, Paul ULg; Jacquet, Nicolas ULg; Delimme, Guy ULg et al

in Journal of Food Engineering (2013), 114(2), 199-206

The size of wheat starch granules was measured during isothermal and non-isothermal treatments and fitted using mathematical models in order to elucidate the time–temperatures dependence of the swelling ... [more ▼]

The size of wheat starch granules was measured during isothermal and non-isothermal treatments and fitted using mathematical models in order to elucidate the time–temperatures dependence of the swelling phenomenon and to improve our understanding of the mechanism followed by granules during gelatinization. Upon the onset temperature of gelatinization, starch granules size increase rapidly and tend to reach equilibrium values that depend on the temperature and heating rate applied. The most accurate fitting of granule size observed overall isothermal treatments was obtained with the third-order kinetic and the Weibull empirical models. The activation energy of swelling calculated for isothermal treatment varied between 41 and 318 kJ mol 1, depending on the mathematical model considered. Therefore, without a consensus on the mechanism and order of reaction followed during gelatinization, the meaningful of kinetic parameters calculated using mathematical models seems highly questionable. During non-isothermal treatments at lower heating rate, it seems like a limitation of the swelling capacity of granules was induced. This phenomenon was attributed to restructuration occurred inside of granules. So, forecasting the swelling behaviour of starch granules during non-isothermal treatment has to consider both the time–temperature and the heating rate applied. [less ▲]

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See detailVers une intégration du sorgho comme matière première pour la brasserie moderne (synthèse bibliographique)
Bwanganga Tawaba, J.-C.; Ba, K.; Destain, Jacqueline ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2013), 17(4), 622-633

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See detailInfluence of processing parameters on physicochemical properties of low-trans and trans-free puff pastry margarines
Lefebure, Emilie ULg; Ronkart, Sébastien; Brostaux, Yves ULg et al

in LWT - Food Science and Technology (2013), 51(1), 225-232

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See detailOptimizing red sorghum malt quality when Bacillus subtilis is used during steeping to control mold growth
Bwanganga Tawaba, Jean-Claude ULg; Bera, François ULg; Thonart, Philippe ULg

in Journal of the Institute of Brewing (2012), 118(3), 295-305

Previous work having shown that Bacillus-subtilis-S499-based biocontrol treatments applied without aeration at the steeping stage of red sorghum malting offered good mould reduction but yielded malts with ... [more ▼]

Previous work having shown that Bacillus-subtilis-S499-based biocontrol treatments applied without aeration at the steeping stage of red sorghum malting offered good mould reduction but yielded malts with low levels of key hydrolytic enzymes, we attempted to raise these levels by aerating the steeping liquor, varying the steeping time (from 8 to 40 h) and temperature (from 25 to 35°C), and combining a biocontrol treatment with prior steeping in 0.2% NaOH. Aeration proved particularly important whenever B. subtilis cells were present in the steep liquor. The optimal temperatures for α- and β-amylase were 30 and 25°C, respectively. By increasing the steeping time it was possible to improve the α-amylase activity, but the -amylase activity peaked sharply between 16 and 20 h, depending on the steeping medium. A good compromise was steeping in biocontrol medium for 14 to 16 h at 30°C. Combination steeping treatments (0.2% NaOH for 8 h followed by biocontrol for 8 h) yielded malts of a quality approaching that afforded by dilute alkaline treatment. [less ▲]

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See detailA Semiochemical Slow-release Formulation in a Biological Control Approach to Attract Hoverflies
Heuskin, Stéphanie ULg; Lorge, Stéphanie ULg; Leroy, Pascal ULg et al

in Journal of Environment and Ecology (2012), 3(1), 72-85

E-β-Farnesene, the alarm pheromone of many aphid species, and E-β-caryophyllene are considered as two sesquiterpenes attractive for aphid predators, among which Syrphidae species. Both compounds were ... [more ▼]

E-β-Farnesene, the alarm pheromone of many aphid species, and E-β-caryophyllene are considered as two sesquiterpenes attractive for aphid predators, among which Syrphidae species. Both compounds were formulated in alginate gel beads as slow-release devices in a biological control approach against aphids. Semiochemical diffusion from beads was studied in the laboratory according to abiotic parameters. Efficiency of formulations as hoverfly attractant was demonstrated in field experiments from June to August 2009. The diffusion of semiochemicals from alginate bead formulations was principally limited by high values (>85%) of relative humidity in the air. Temperature also impacts the release of volatile compounds. In field experiments, these two abiotic factors were supposed to highly condition the trapping of hoverflies. These field trappings demonstrated the efficiency of both semiochemical formulations compared to control (formulation without semiochemical) to catch females of Syrphidae during three months. [less ▲]

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See detailInfluence of drying and hydrothermal treatment of corn on the denaturation of salt-soluble proteins and color parameters
Odjo, Sylvanus; Malumba Kamba, Paul ULg; Dossou, Joseph et al

in Journal of Food Engineering (2012), 109(3), 561-570

The effect of heat treatments (drying and hydrothermal treatment) on the extractability of salt-soluble protein (SSP) was assessed using Promatest methodology for corn kernels heated between 60 C and 120 ... [more ▼]

The effect of heat treatments (drying and hydrothermal treatment) on the extractability of salt-soluble protein (SSP) was assessed using Promatest methodology for corn kernels heated between 60 C and 120 C. During drying, the evolution of the grain moisture content is fitted using the analytical solution of Fick equation developed by Crank (1979) for spherical material. The decrease of extractible salt-soluble protein during heating is forecasted using a first and a second order ordinary differential equation. It was found that temperature; moisture content and time of processing greatly influence the kinetic denaturation of SSP of corn kernels. The evolution of extractible SSP content of corn kernels during drying at high temperature is more correctly described with second order kinetic than with the first order kinetic reaction. The Hunterlab color parameters of corn also vary during drying. Lightness and color intensity decrease while yellowness, redness, chroma and hue angle increase through drying time. Most of these Hunterlab color parameters are highly correlated with the salt-soluble proteins content and therefore could be used as indicators of excessive heat treatment and denaturation of salt-soluble proteins in corn kernels [less ▲]

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See detailUse of Bacillus subtilis S499 to control mould growth during malting of red sorghum from the D.R. of Congo
Bwanganga Tawaba, Jean-Claude ULg; Destain, Jacqueline ULg; Bera, François ULg et al

Poster (2011, November)

In this work, moulds growth was monitored during malting of a red sorghum from D.R. of Congo. Results obtained with chemical treatments [diluted alkalines: NaOH 0.2% (T1) and Ca(OH)2 0.1% (T2)] were ... [more ▼]

In this work, moulds growth was monitored during malting of a red sorghum from D.R. of Congo. Results obtained with chemical treatments [diluted alkalines: NaOH 0.2% (T1) and Ca(OH)2 0.1% (T2)] were compared with those of biocontrols [use of Bacillus subtilis S499 108 cells / mL: supernatant + cells (T3), cells (T4) and cells-free supernatant (T5)]. Chemical treatments have shown the highest fungal contamination levels, the highest malting loss, but better enzyme activities (α and β-amylases, limit-dextrinase, α-glucosidase and β-glucanase). The inhibition tests showed that the concentration of lipopeptides is correlated with the reduction of moulds growth. Malting trials with starters of Bacillus subtilis S499 showed that culture dilution affects the growth of moulds during red sorghum malting. The combination of a chemical treatment such as diluted NaOH with a biocontrol could be used to improve sorghum malts quality in terms of different enzymes activities and by reducing the level of fungal contamination. Key words: Bacillus subtilis S499, mould, sorghum malting [less ▲]

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See detailInfluence of the processing parameters on the physicochemical properties of puff pastry margarines
Lefebure, Emilie ULg; Ronkart, Sébastien; Brostaux, Yves ULg et al

Poster (2011, September 18)

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See detailINFLUENCE OF DRYING TEMPERATURE ON THE CORN WET-MILLING PROCESS: REVIEW
Malumba Kamba, Paul ULg; Janas, Sébastien; Sindic, Marianne ULg et al

in Filipovic, Lovro, A. (Ed.) Milling: Operations, Applications and Industrial Effects (2011)

In order to separate its major components, corn kernel is processed using the wet-milling process during which steeping, milling and starch/gluten separations appear to be the most important operations ... [more ▼]

In order to separate its major components, corn kernel is processed using the wet-milling process during which steeping, milling and starch/gluten separations appear to be the most important operations. To improve the efficiency of this process, corn wet-milling industry expended considerable resources focusing on improved process control, more efficient process equipment and on the development of hybrids that decrease the variability and reduce production costs. However, important variability is still observed according to the thermal history of grain after harvesting. The present article reviews up-to-date literature on the effect of drying conditions on the corn wet-milling performance and the physicochemical and functional properties of corn wet-milled fraction. Literature in this topic shows that high drying temperature combined with high initial moisture content of grain impact significantly the wet-milling performance and the quality of recovered materials. Further studies on the influence of drying process on the quality of starch, gluten, germ and fiber recovered during the wet-milling process are needed and would help to develop more accurate engineering and economic models for the corn wet milling process. [less ▲]

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See detailStructure de l’amidon de maïs et principaux phénomènes impliqués dans sa modification thermique
Malumba Kamba, Paul ULg; Janas, Sébastien ULg; Deroanne, Claude et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(2), 315-326

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See detailTechniques de séchage des starters lactiques et mécanismes affectant la viabilité cellulaire suite à la lyophilisation
Coulibaly, Ibourahema ULg; Dubois Dauphin, Robin ULg; Danthine, Sabine ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(2), 287-299

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See detailModelling dehydration and quality degradation of maize during fluidized-bed drying
Janas, Sébastien ULg; Boutry, Sébastien; Malumba Kamba, Paul ULg et al

in Journal of Food Engineering (2010), 100(3), 527-534

At harvest time, maize (Zea mays L.) has a moisture content too high to be stored, and has to be dried. To control the previous termdryingnext term impact on maize characteristics, it is necessary to ... [more ▼]

At harvest time, maize (Zea mays L.) has a moisture content too high to be stored, and has to be dried. To control the previous termdryingnext term impact on maize characteristics, it is necessary to accurately know the spatial distribution of temperature and moisture content in the kernel, and the kinetics of quality loss in relation to these two factors. To this end, a physical model of heat and mass transfer in a maize kernel was designed. The Fick and Fourier equations were solved by the finite element method (FEM). The real 3D geometry of maize was obtained by NMR imaging and then used to build the mesh needed for the FEM computations. The model correctly describes the evolutions of maize moisture and salt-soluble protein content during fluidized-bed previous termdryingnext term with a constant previous termdryingnext term air temperature between 50 °C and 100 °C. [less ▲]

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See detailComparaison d’un modèle empirique et d’un modèle physique de séchage de grains de maïs en lit fluidisé
Janas, Sébastien ULg; Malumba Kamba, Paul ULg; Deroanne, Claude et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(3), 389-398

Dans cet article, deux modèles prévisionnels de la température et de la teneur en eau de grains de maïs durant leur séchage en lit fluidisé sont comparés. Le premier modèle est un modèle empirique, où les ... [more ▼]

Dans cet article, deux modèles prévisionnels de la température et de la teneur en eau de grains de maïs durant leur séchage en lit fluidisé sont comparés. Le premier modèle est un modèle empirique, où les phénomènes physiques impliqués dans le processus ne sont pas décrits. Ses équations peuvent être résolues à l’aide de logiciels gratuits disponibles sur Internet. Le second est un modèle plus complexe, basé sur les lois physiques régissant les transferts de chaleur et de masse au sein du produit. Sa résolution nécessite l’utilisation de logiciels commerciaux de calcul par éléments finis. Les deux modèles sont paramétrés sur des séchages à température constante, puis validés sur des séchages à température variable et un séchage discontinu. Les deux modèles permettent de décrire avec une précision acceptable les évolutions de teneurs en eau au cours des séchages continus et de prévoir les évolutions de teneurs en eau lors des séchages à température variable et du séchage discontinu. Le modèle empirique ne permet pas de décrire l’évolution de la température des grains lors de séchages à température variable avec une précision meilleure qu’1 °C. Si cette précision est suffisante, l’exploitation du modèle empirique permettra de réduire considérablement les couts en temps et en licence de logiciels pour la modélisation du séchage du maïs en lit fluidisé. [less ▲]

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